Project Summary Bladder cancer is the sixth most common cancer diagnosis in the U.S. Although three-quarters of patients are diagnosed early with superficial (non-invasive) disease, bladder cancer is highly recurrent and requires long-term maintenance therapy and costly continuous surveillance. Novel therapies, capable of inducing durable anti-tumor responses, are needed to limit progressive recurrence and to improve survival. Immune-based therapies have demonstrated the potential to elicit, durable tumor-specific immunity. In particular, the pro-inflammatory cytokine, interleukin-12 (IL-12), has demonstrated remarkable anti-tumor activity and protective immunity in numerous preclinical tumor models. Previous research has demonstrated that chitosan, a natural polysaccharide derived from the exoskelatons of crustaceans, can enhance the anti- tumor efficacy of intravesically administered IL-12. Co-formulations of chitosan solution and IL-12 (chitosan/IL- 12) were found to eliminate established orthotopic bladder tumors and generate systemic tumor-specific protective immunity. The proposed project will continue the preclinical development of intravesical chitosan/IL-12 immunotherapy. Three independent aims are proposed. Aim 1 is designed to elucidate the mechanisms by which chitosan facilitates intravesical IL-12 delivery. Aim 2 will assess the pharmacokinetics, safety and tolerability of intravesical chitosan/IL-12 immunotherapy using clinically relevant endpoints. Aim 3 will begin to describe how an intravesical immunotherapy can generate systemic protective immunity. The overall goal of this project is to improve our mechanistic understanding of chitosan-enhanced intravesical delivery while providing critical preclinical data in support of translation of a promising new immunotherapy for the treatment of bladder cancer. At the same time, this project will enhance the biomedical research capacity at an AREA institution, provide valuable research opportunities for 2 new graduate students and expose approximately 15-25 undergraduate students to biomedical research.